With all that theory spinning around in our heads, it's time to do something practical. Let's start by setting up the user authentication service. We'll call this AuthNet, and it comprises a MySQL instance to store the user database, the authentication server, and a private subnet to connect them.
It is best for each container to focus on providing one service. Having one service per container is a useful architectural decision because we can focus on optimizing each container for a specific purpose. Another rationale has to do with scaling, in that each service has different requirements to satisfy the traffic it serves. In our case, we might need a single MySQL instance, and 10 user authentication instances, depending on the traffic load.
